Frozen confectionery products

ABSTRACT

A method for producing frozen confectionery products comprising a coagulated protein system contributes to the improvement of textural and sensorial attributes of the confections, in particular of products based on lower fat formulations. Such a protein system is used in frozen confection prepared by conventional freezing alone or combined with low temperature freezing wherein it improves the microstructure and stability on frozen products.

PRIORITY CLAIM

The present application is a divisional of U.S. patent application Ser.No. 13/813,603 filed on Jan. 31, 2013, which is a National Stage ofInternational Application No. PCT/EP11/062623 filed on Jul. 22, 2011,which claims priority to European Application No. 10171988.8 filed onAug. 5, 2010, the entire contents of each incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to a method for producing frozenconfectionery products. In particular, the invention is concerned amethod for producing frozen confections comprising a coagulated proteinsystem which contributes to the improvement of textural and sensorialattributes of the confections, in particular of products based on lowerfat formulations. Such a protein system is used according to theinvention in frozen confection prepared by conventional freezing aloneor combined with low temperature freezing wherein it improves themicrostructure and stability on frozen products. Products obtained bysaid method also form part of the invention.

BACKGROUND OF THE INVENTION

Many technical routes have been explored in the prior art to improve thesensorial properties of low fat formulations used for the preparation ofice confections.

Low-temperature extrusion or low-temperature freezing is a technologythat has been recently developed and which has been used to conferenhanced organoleptic properties to frozen confectionery products.Examples of such frozen confectioneries include ice cream, frozenyogurt, sorbet etc.

Such a method is described for instance in a general way in thefollowing published documents: WO 2005/070225, WO 2006/099987, EP0713650, U.S. Pat. No. 7,261,913 and more recently US 2007-0196553.

The products obtained by low-temperature extrusion have a particularmicrostructure as extensively described in Ph.D. Dissertation ofWildmoser J. submitted to the Swiss Federal Institute of Technology ofZurich in 2004, “Impact of Low Temperature Extrusion Processing onDisperse Microstructure in Ice Cream Systems”.

Low temperature extrusion is used in the manufacturing of reduced andlow fat frozen confectioneries wherein this technology is helping tocompensate for the effect of a low fat content on the texture andmouthfeel of the product.

The prior art also discloses ways to improve the texture of low fat iceconfection products prepared by conventional freezing through the use ofspecific emulsifiers. However, these additives are often perceivednegatively by the consumer and solutions that get rid of suchingredients are highly sought.

Besides, consumers' demand continuously increases for “better for you”types of products with lower fat contents or even non fat products,while not compromising on taste. There is therefore a need to improvethe results obtained here thereto and to improve the sensory profile ofexisting products.

SUMMARY OF THE INVENTION

The present invention now solves the foregoing problems by providing amethod for providing a stable frozen confectionery product havingenhanced or improved organoleptic properties.

In a first aspect, the invention relates to a method of producing afrozen confectionery product wherein controlled heat and acidicconditions are firstly applied to a composition comprising at least 7 wt% of dairy protein. According to a particular embodiment, saidcomposition essentially consists of a mixture of whey protein, skim milkand water.

The coagulated protein system is then mixed with further ingredients toform a confectionery mix which is pasteurized and then frozen, either byconventional freezing or by further low temperature extrusion, toproduce the frozen confectionery product.

More particularly, a method of producing a frozen confectionery product,comprising the steps of:

a) subjecting a composition comprising at least 7 wt % of dairy proteinwith a pH comprised between 5.6 and 6.5, to a heat treatment at atemperature between 80° and 140° C. for a time period of 5 seconds to 30minutes to at least partially form a coagulated protein system includingcasein and whey protein;

b) optionally homogenising said composition before or after the heattreatment;

c) mixing said composition with further ingredients to form an iceconfectionery mix;

d) pasteurizing the confectionery mix;

e) freezing while optionally aerating the confectionery mix, preferablyto an overrun of at least 20%, preferably at least 40%, most preferablybetween 100% and 120% to form the frozen confectionery product;

f) optionally subjecting the confectionery product to a dynamic coolingat a temperature below −11° C.;

g) optionally hardening the confectionery product is part of the presentinvention.

The frozen confectionery products obtainable by this method also form anembodiment of the present invention.

The products obtainable by the invention present excellent organolepticproperties, in particular in terms of texture and mouthfeel even whenvery low levels of fat are used.

Besides, the products show good stability and can thereforeadvantageously allow avoiding the use of non-natural additives.

In the products of the invention, the coagulated protein system includesmilk proteins, caseins, whey proteins or mixtures thereof that have beencoagulated by a heat treatment in a mild acidic environment e.g. throughthe presence of molasses or of an organic acid. More particularly, thecoagulated protein system of the products of the invention includescasein and whey protein including beta-lactoglobulin in the form ofcomplexes or aggregates. The coagulated protein system is generallypresent in an amount sufficient to provide a smooth and creamy textureto the confectionery product without the use of non-natural stabilizersor other conventional artificial additives used for this purpose.Typically, the coagulated protein system is present in the frozenconfectionery product in an amount of 0.5 to 4 wt %.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, the % values are in wt % unless otherwisespecified.

When reference is made to the pH, values correspond to pH measured at25° C. with standard equipment.

The invention pertains to an optimized process of preparation of frozenconfectioneries including the controlled use of heat in acidicconditions applied to a mix comprising at least 7 wt % proteins, furtherused as an ingredient in a frozen confectionery mix to be processed.

Preferably, the treated mix comprising at least 7 wt % dairy proteinsdoes not undergo any drying, rehydration or concentration step beforebeing mixed with the other ingredients to form an ice confectionery mix.

By “frozen confectionery product” is meant any frozen product such asice cream, sorbet, mellorine or any frozen dessert etc. The product maybe aerated.

A method for producing frozen confectionery products forms part of theinvention, and more particularly a method of producing a frozenconfectionery product comprising firstly producing a coagulated proteinsystem and combining said system with a confectionery mix which isfurther optionally homogenised and pasteurised, and conventionallyfrozen or subjected to low temperature extrusion.

According to a particular embodiment, the method comprises as a firststep providing a composition comprising at least 7% of dairy protein.The composition is preferably an aqueous composition comprising dairyprotein in an amount such that the amount of dairy protein in the finalproduct is less than 7%, preferably between 2% and 4% dairy protein.

Sources of dairy protein typically include liquid fresh milk, milkpowder, standardised milk powder, skimmed milk powder, acid casein,sodium caseinate, acid whey, whey protein concentrate, whey proteinisolate, sweet whey, demineralised sweet whey, demineralised whey or anymixtures thereof

The composition is heat treated to at least partially form a coagulatedprotein system including casein and whey protein.

The term “coagulated protein system” is to be understood to mean acomplex or an aggregate resulting from at least a partial coagulation ofproteins present in a composition comprising dairy protein.

The heat treatment is carried out at a temperature of between 80 and140° C. for a time period of 5 seconds to 30 minutes. Alternatively theheat treatment can be performed at lower temperatures such as between60° and 80° C. with a longer hold time.

The composition heated has a pH value between 5.6 and 6.5, morepreferably between 5.8 and 6.3.

Unless otherwise specified, reference to the pH in the context of theinvention corresponds to the pH measured at room temperature before heattreatment.

In a particular embodiment, the composition comprising at least 7% dairyprotein has a pH of 5.6 to 6.5, preferably 5.8 to 6.3, and is subjectedto a heat treatment at a temperature between 80 and 90° C. for a timeperiod of 5 seconds to 30 minutes.

In said embodiment, the pH of the composition comprising a source ofdairy protein is thus reduced to a value of 5.6-6.5, preferably 5.8-6.3.This is typically achieved by including an acidic component such asthose selected from liquid molasses, organic acids, such as citric acid,ethylenediaminetetraacetic acid (EDTA), fruit derived acids.

Alternatively, the composition comprising a source of dairy protein maybe heated to a temperature above 90° C. up to 140° C., preferably95-135° C., more preferably 100-130° C., for a time period of 5 secondsto 30 minutes. The composition has a pH comprised between 5.6 and 6.5before being heat-treated.

Preferably, the composition comprising a source of dairy protein is notfermented.

Typically, at least 30%, preferably at least 45%, more preferably atleast 60% of dairy protein is converted to said coagulated proteinsystem.

Once the coagulated protein system has been produced, the compositionmay be homogenised. Typically, homogenisation is carried out at apressure of between 40 and 200 bars, preferably between 100 and 150bars, more preferably between 120 and 140 bars. In an embodiment,homogenisation may be carried out prior to the heat treatment.

The composition which, after heat treatment, comprises the coagulatedprotein system is then mixed with further ingredients to form an iceconfectionery mix. Typically, the further ingredients include any offat, sweetening agents, milk solids non-fat, stabilisers, emulsifiers,flavours, colourings, proteins, water, acidifying components,alkalinising components, or any mixtures thereof.

The confectionery mix thus typically comprises fat, preferably in anamount of 0.5-20%, milk solids non-fat, preferably in an amount of5-15%, sweetening agent, preferably in an amount of 5-30%.

By “sweetening agent” it is to be understood ingredients or mixture ofingredients which impart sweetness to the final product. These includenatural sugars like cane sugar, beet sugar, molasses, other plantderived nutritive sweeteners, and non-nutritive high intensitysweeteners. Typically, the sweetening agents are selected from dextrose,sucrose, fructose, corn syrups, maltodextrins, erythritol, sorbitol,aspartame, sucralose, steviolglycosides or any mixtures thereof.

A stabiliser system, preferably a natural stabiliser system, may also beincluded in an amount up to 6%.

By “stabiliser system” is to be understood a mixture of ingredientswhich contributes to the stability of the frozen product with respect toice crystal formation, heat shock resistance, overall texture propertiesetc. Thus, the stabiliser system may comprise any ingredients which areof structural importance to the frozen confectionery.

The stabiliser system used in the present invention is preferablyessentially or completely free of any artificial or non-naturalemulsifier or stabiliser.

The stabiliser system used in the present products preferably comprisesat least one emulsifier, preferably at least one natural emulsifier.

Natural emulsifiers include for example egg yolk, buttermilk, raw orprocessed acacia gum, lecithin (soy, sunflower, safflower or other plantderived lecithin), natural plant extracts (e.g. Q-Naturale®), rice branextract or mixtures thereof. The natural emulsifiers have the advantageof conferring to the finished product a smoother texture and stifferbody which reduce the whipping time. The presence of natural emulsifiersresults in air cells that are smaller and more evenly distributedthroughout the internal structure of the ice cream. Preferably, thenatural emulsifier used in the present stabiliser system is egg yolk.Typically, the ice confectionery mix comprises 0.5 to 1.4% egg yolksolids.

According to a specific embodiment, the product of the inventionessentially consists in natural ingredients.

Therefore, the ice confectionery mix does not include any artificial ornon-natural emulsifier or stabiliser.

By “natural ingredients” what are meant are ingredients of naturalorigin. These include ingredients which come directly from the field,animals, etc. or which are the result of a physical ormicrobiological/enzymatic transformation process. These therefore do notinclude ingredients which are the result of a chemical modificationprocess.

Examples of non-natural ingredients which are avoided in this particularembodiment of the invention include for example mono- and diglyceridesof fatty acids, acid esters of mono- and diglycerides of fatty acidssuch as acetic, lactic, citric, tartaric, mono- and diacetyl tartaricacid esters of mono- and diglycerides of fatty acids, mixed acetic andtartaric acid esters of mono- and diglycerides of fatty acids, sucroseesters of fatty acids, polyglycerol esters of fatty acids, polyglycerolpolyricinoleate, polyethylene sorbitan mono-oleate, polysorbate 80,chemically extracted lecithin.

Chemically modified starches which are used in the art as stabilisersare also preferably avoided. These include for example oxidised starch,monostarch phosphate, distarch phosphate, phosphated or acetylateddistarch phosphate, acetylated starch, acetylated distarch afipate,hydroxy propyl starch, hydroxypropyl distarch phosphate, acetylatedoxidised starch.

The products of the invention are preferably essentially free of thepreceding synthetic esters and modified starches. “Essentially free”means that these materials are not intentionally added for theirconventional property imparting abilities, e.g. stabilizing, althoughthere could be unintended minor amounts present without detracting fromthe performance of the products. Generally and preferably, the productsof the invention will not contain any non-natural materials.

The products may thus include a natural stabilizer system such as thosedescribed in application EP 08171666.4, the entire content of which isexpressly incorporated herein by reference thereto.

According to another particular embodiment, the stabiliser system usedin the products of the invention comprises at least one non-naturalemulsifier. Any food grade emulsifier typically used in ice confectioncould be used. Suitable emulsifiers include sugar esters, emulsifyingwaxes such as beeswax, carnauba wax, candedilla wax, plant or fruitwaxes and animal waxes, polyglycerol fatty acid esters, polyglycerolpolyricinoleate (PGPR), polysorbates (polyoxyethylene sorbitan esters),monoglycerides, diglycerides, lecithin and mixtures thereof.

A hydro-colloid such as agar, gelatine, gum acacia, guar gum, locustbean gum, gum tragacanth, carrageenan, carboxymethylcellulose, sodiumalginate or propylene glycol alginate or any mixture of hydrocolloidscan also be present in the stabilizer system.

The product may additionally comprise flavourings or colourings. Suchflavourings or colourings, when used, are preferably selected fromnatural ingredients. These are used in conventional amounts which can beoptimized by routine testing for any particular product formulation.

Preferably, mixing of the composition comprising the coagulated proteinsystem with further ingredients is carried out such that the resultingconfectionery mix has a content of coagulated protein system of 0.5 to4%.

The confectionery mix is then pasteurized under standard conditions,typically at 86° C. during 30 seconds before being cooled to around 2 to8° C. by known means. The mix may further be aged for 4 to 72h at around2 to 6° C. with or without stirring. Optionally, the addition offlavourings, colourings, sauces, inclusions etc. may be carried outprior to the ageing step. If flavourings, colourings, sauces, inclusionsetc. are added, these are preferably selected from natural ingredientsonly.

In the next step, the mix may be aerated. In a preferred embodiment, themix may be cooled to a temperature below −3° C., preferably between −3°and −10° C., preferably at about −4.5° to −8° C. with stirring andinjection of gas to create the desired overrun.

The frozen confectionery is preferably aerated to an overrun of at least20%, preferably at least 40%, more preferably at least 90%. The overrunis preferably up to 150%. Most preferably, the overrun is comprisedbetween 100-120%.

The mix is then subjected to freezing either by using conventionalfreezing equipment or by a low temperature extrusion system. Thus, theconfectionery mix may be optionally subjected to a dynamic cooling at atemperature below −11° C. In this equipment, the aerated mix is cooledby extrusion at a temperature of below −11° C., preferably between −12°C. and −18° C. in a screw extruder. The screw extruder may be such asthat described in WO 2005/070225.

The extrusion may be performed in a single or twin screw extruder.

According to the present method, the frozen confectionery products canbe produced by conventional freezing or by low-temperature extrusion.

A low temperature extruded frozen confectionery comprising thecoagulated protein system defined above is thus another object of thepresent invention. This step of low-temperature extrusion (LTE) orlow-temperature freezing (LTF) may be carried out in a single or twinscrew extruder. By low-temperature extrusion (or low-temperaturefreezing) is meant extrusion at a temperature of below −11° C.,preferably between −12° C. and −18° C.

Low-temperature extrusion (LTE) is a known process which imparts to thefinal product a specific and advantageous microstructure. For instance,ice crystal size and air bubble size tend to be smaller than intraditional manufacturing processes. On the other hand, the size of fatglobules does not change significantly when LTE process is used.

When low-temperature extruded or low-temperature frozen, the products ofthe invention surprisingly present improved characteristics in terms oftheir microstructure compared to known low temperature extrudedproducts.

Products obtained by low temperature freezing (LTF) are described in US2007/0196553, the content of which is here-included by reference. Forinstance, ice crystal size and air bubble size tend to be smaller thanin traditional manufacturing processes. Ice crystals, air cells, fatglobules and agglomerates thereof shall be in a specific diameter rangein order to enhance positive sensory and stability characteristics.Typically at least 50% in number of ice crystals/ice crystalagglomerates preferably in a size range between 5 and 30 microns (ormean value below 8-10 microns) together with a low degree of ice crystalinterconnectivity improve scoopability and creaminess. At least 50% innumber of air cells preferably in the diameter range between 2-10microns (or mean value below 8-10 microns) delays bubble coarsening bycoalescence during melting in the mouth so strongly, that creaminesssensation is significantly enhanced. The volume-averaged sizedistribution of fat globules/fat globules agglomerates preferablyexhibits a peak in the size range between 2-20 microns. This sizedistribution represents the relative volume of fat globules of eachspecified diameter and has a significant direct impact on improvingcreaminess sensation in the mouth and also contributes to increased aircell structure stability against coalescence thus supporting alsoindirectly the creaminess attribute. These size measurements can becarried out by methods known to the skilled person. For instance, icecrystal size and air bubble size can be measured using opticalmicroscopy and fat particle size analysis can be carried out by laserlight scattering.

The low-temperature extruded frozen aerated confectionery products ofthe invention have a smoother mouthfeel and particularly appealingtextural and organoleptic properties, compared to low-temperatureextruded products known to date.

In terms of microstructure, the products of the invention can becharacterised by an average equivalent diameter (D₂₁) of fat globule orfat globule agglomerates below 10 microns. This value can bequantitatively analysed in fluorescence microscopy of resin sections ofcryo-fixed (−20° C.) and resin cryo-infiltrated (−20° C.) ice creams ata magnification of x1440. Therefore, compared to a standard LTF process,the combination of LTF with the inclusion of coagulated protein systemaccording to the invention leads to an intermediate size of fatglobules.

Therefore, it has been surprisingly found out that the presence of acoagulated protein system according to the invention in a lowtemperature extruded product tremendously improves the sensory profileof the product and in particular that it enhances considerably thesmooth and creamy texture of frozen confectioneries that contain thissystem.

This effect is even more surprising given that it is known from the artthat protein coagulation has a negative impact on the organolepticcharacteristics of ice cream products. In this regard, EP 1 342 418teaches a method for preparing a frozen ice cream containing an acidcomponent but ensuring that at least one protein does not react with theacid. According to this teaching, the contact time between the acid andthe protein should be kept to a minimum.

In contrast, the present invention is directed to a coagulated proteinsystem produced by a heat treatment, optionally in acidic conditions,which has been shown to considerably improve the texture of frozenconfections prepared either by conventional freezing or by lowtemperature freezing.

When conventional freezing is used, the partial coagulation obtained bycontrolled application of heat and optionally acidic conditions to themix results in exceptional sensory attributes which are comparable tothose obtained by low temperature extrusion without such partialcoagulation.

On the other hand, when low temperature extrusion is used, the inclusionof a coagulated protein system during mix processing and low temperatureextrusion technology, allows the creation of very high quality frozenconfectionery with a minimum of fat and fewer ingredients. While the useof low temperature extrusion to manufacture low fat ice cream has beenwidely practiced, the invention now creates a significantly superiorproduct and hence unique advantage for the consumer.

Furthermore, the product of the invention has proven to be particularlystable, both when frozen as well as when dispensed at room temperaturefor consumption.

Without being bound by theory, it is believed that a coagulated proteinsystem within the frozen confectionery mix is providing freshlycoagulated protein that act as a natural stabilizer for the air cellsand enable creation of a very fine and stable microstructure resultingin a smooth, rich and creamy product without the use of artificial ornon-natural stabilizers or similar additives. This makes the productsmore natural and desirable for consumers who wish to minimize theirintake of such artificial or non-natural additives.

In particular, the synergistic effect of the freshly coagulated proteinsin the amounts used when combined with the LTF technology is thereforeleading to superior products in terms of texture and stability.

Optionally, the confectionery mix is then hardened. The frozen mix isthus preferably packaged and stored at temperatures below −20° C., whereit will undergo hardening step during storage. Alternatively, it can behardened by accelerated hardening step, for example via a hardeningtunnel, carried out at a temperature between −20° C. to −40° C. for asufficient time to harden the product.

The process of the invention has surprisingly proven to enhance thetextural experience of frozen dairy systems even at lower fat andcalorie levels. The applicant has discovered that combination of apre-mix comprising a coagulated protein system with confectioneryproduct ingredients results in a product with smooth, creamy texture andsuperior flavour release when compared to typical low temperatureextruded products. Without being bound by theory, it is believed thatduring the process, protein structure changes as heat unfolds wheyproteins and destabilizes casein micelles. The modified protein forms acontrolled network that binds water and fat globules while increasingmix viscosity to create a uniquely smooth and creamy texture that mimicsthe sensory attributes of higher fat products.

The frozen aerated confectionery products obtainable by the presentmethod also form part of the invention.

The products obtainable by the present method preferably comprise 0.5 to4% of coagulated protein system.

The term “coagulated protein system” is to be understood to mean acomplex or an aggregate resulting from at least a partial coagulation ofproteins present in a composition comprising dairy protein, for instanceinduced by a heat treatment, preferably in the presence of an acidcomponent.

The process of the invention impacts the obtained product in such a waythat compared to a process were no such specific heat and acidicconditions are used, one observes an increase in the volume of particlesbetween 1 and 10

In the present disclosure, the terms “particle size” are meant todesignate D_([3,2]). D[_(3,2)] is the equivalent surface area meandiameter or the Sauter mean diameter of the particles of the coagulatedprotein system aggregated with fat as measured by laser diffraction one.g. a Mastersizer Micro Particle Size Analyzer, from MalvernInstruments Ltd (UK). These particle sizes can be measured in the mix aswell as in the end product. For measurements, samples are dispersed inwater and measured according to the instructions of the instrumentmanufacturer. Frozen samples are allowed to melt before measuring. Whenthe process of the invention is applied one observes an increase ofD[_(3,2)] of up to 60% depending on the used formulation.

The particle size distribution of a formulation (ice cream mix) thatdoes not contain coagulated proteins is different from the sameformulation that is treated according to the process of the inventionwhich causes partial coagulation of the proteins in the formulation.

In particular when the process of the invention is applied, the volumeof particles below 1 micron i.e. the fraction of particles expressed in% of volume that are below 1 micron is reduced up to 60% and the volumeof particles between 1 and 10 microns is increased up to 140%.

Thus, the present coagulation treatment creates a three dimensionalnetwork that has the ability to have increased water binding capacityand results in an improvement of sensory attributes relating to textureand flavour.

Such a system offers the unexpected advantage that it can confer to thefrozen confectionery product exceptional sensory attributes with goodstability while minimizing the fat content.

Preferably, the proteins at the origin of the coagulation are milkproteins which comprise caseins and whey proteins.

Products obtainable by the present method typically comprise 0.5-20%fat, 5-15% MSNF, 5-30%, preferably 15-25% of a sweetening agent.Preferably, the amount of fat is less than 15%, more preferably from 0.5to 12% and even more preferably 0.5-5.5%. They may also comprise anatural stabilizer in an amount of 0 to 6%. The amount of protein insuch products is preferably less than 7%, preferably 2-4%.

The products may be aerated to an overrun of at least 20%, preferably atleast 40% and more preferably at least 90%. In a most preferredembodiment, the overrun is 100-120%.

Preferably, the product is not fermented.

The product obtainable by the present method may be furthercharacterised by a non-sedimentable protein content below or equal to60%, preferably below 50%.

What is meant by “non-sedimentable protein”, or non soluble protein,“non-sedimentable casein” or yet “non-sedimentable whey protein” is theamount of corresponding protein in the soluble fraction of the iceconfection once melted at room temperature (25° C.) and centrifuged at50,000 g for 30 min using for example a Sorvall RC-5 plus centrifugeequipped with a SM 24 rotor or an equivalent device enabling to applysimilar acceleration during the same time.

The content of non-sedimentable or “soluble” protein in theconfectionery product is inversely proportional to the amount ofcoagulated protein system in said product. Thus, an important amount ofcoagulated protein system in the confectionery product will reduce theamount of non-sedimentable protein in said confectionery product.

The coagulated protein system is obtainable by subjecting a compositioncomprising at least 7 wt % of dairy proteins to a heat treatment at atemperature of between 80 and 90° C. at a pH between 5.6 and 6.5,preferably between 5.8 and 6.3. Alternatively, the coagulated proteinsystem is obtainable by subjecting a composition comprising dairyproteins to a heat treatment at a temperature above 90° C. up to 140°C., preferably 95-135° C., more preferably 100-130° C., preferably at apH comprised between 5.6 and 6.5.

The time period for the heat treatment is typically 5 seconds to 30minutes.

Acidic conditions are required to form the coagulated protein system.Any acidic component such as those selected from liquid molasses,organic acids, such as citric acid, ethylenediaminetetraacetic acid(EDTA) or fruit derived acids.

Most milk proteins (mainly caseins) in their native state remain incolloidal suspension form leading to minimal changes to mix viscosity(˜200-400 cp). However, when proteins are subjected to controlledexposure to known amounts of heat and acid (e.g. pH of 6.1 or less),they undergo coagulation. Coagulation is a state where the proteins arehydrated resulting in a three dimensional network (soft gel) causingincreased mix viscosity (˜1800-2400 cp). If the exposure of proteins toheat and optionally acid is not controlled, this phenomenon could leadto precipitation (e.g. syneresis in yogurt). In the worst case scenario,the liquid separates from the precipitate and the size of the solidsdecreases.

The applicant has discovered that texture and mouthfeel of iceconfections is improved as a result of an optimized process ofpreparation including the controlled use of heat and optionally acidicconditions. More particularly, by manipulating the milk proteinstructure in a composition to be added to an ice confection mix byexposing the dairy protein to controlled heat and decreasing the pH, itis believed that protein denaturation and subsequent aggregation occursas heat unfolds whey protein and destabilizes casein micelles. Theseprotein aggregates form a network that is suspected of entrapping waterand fat globules and increases mix viscosity to create a uniquelysmooth, creamy texture that mimics the presence of higher fat levels.

It can therefore be concluded that the process described in the presentinvention is leading to the formation of covalent complexes (probablylinked by disulphide bonds) between casein and whey protein and thatthese complexes are more numerous in the control sample (higher initialcasein band density). Without being bound by theory, it is believed thatcasein micelles are coated with whey protein includingbeta-lactoglobulin under the heat and acidic conditions of the presentinvention and are either entrapped in the fat phase or in the insolublephase after centrifugation, leading to a depletion of the proteinaggregates in the soluble phase. The non-sedimentable aggregates aremainly composed of whey protein and casein complexes that did not adsorbwith the casein micelles to the fat droplet interface during ice creammanufacture or were not sensitive to centrifugation, but remained in thebulk phase. The coagulated protein system of the invention thereforeconsists on the one hand in casein micelles/whey protein complexes whichcan be defined as covalent protein aggregates formed between thekappa-casein from the surface of the casein micelles. On the other hand,the coagulated protein system consists mostly in non-sedimentablecasein/beta-lactoglobulin complexes present in the frozen confectionbulk.

The amount of casein and whey protein as beta-lactoglobulin can bemeasured from Coomassie Blue gel electrophoresis analysis. The contentof these two proteins can be determined from analysis of the intensityof the corresponding migration bands on reduced electrophoresis Nu-PAGEgels.

Method:

For total sample, an aliquot of 10 g of melted ice cream was dispersedin 90 g of a deflocculating aqueous solution at pH 9.5 containing 0.4%EDTA and 0.1% Tween 20. The soluble phase was obtained by centrifugationof the melted ice cream at 50,000 g for 30 min. Samples were thenanalyzed by gel electrophoresis on Nu-PAGE 12% Bis-Tris using the MOPSrunning buffer in reducing and non-reducing conditions (reducingconditions should break any covalent bound involving SH/SS exchangeduring heating) as described in “Invitrogen Nu-PAGE pre-cast gelsinstructions” (5791 Van Allen Way, Carlsbad, Calif. 2008, USA). Gelswere stained with Coomassie blue (Invitrogen kit no. LC6025). The totalsample and the corresponding soluble phase were deposited on the sameelectrophoresis gel at a concentration of 0.5 mg.mL⁻¹. After migrationand staining with colloidal blue, the gels were scanned in 256 graylevels with a resolution of 1000 dpi using a UMAX scanner coupled withthe MagicScan 32 V4.6 software (UMAX Data Systems, Inc.) leading topictures having a size of 16 MB. These pictures were then analyzed usingthe TotalLab TL120 v2008.01 image analysis software (Nonlinear DynamicsLtd, Cuthbert House, All Saints, Newcastle upon Tyne, NE1 2ET, UK).Migration lanes were detected automatically by the software. Then, imagewas corrected for background using the “rolling ball” option with aradius of 200. Protein bands corresponding to bovine serum albumin(BSA), β-casein, αs1- and as2-casein, casein, β-lactoglobulin (β-1g) andα-lactalbumin (α-1a) were detected manually using the migration bandsfrom a skimmed milk as a standard. The intensity of the bands wasconverted into peak migration profiles for each migration lane for thetotal sample and the soluble phase. These peaks were then fitted with aGaussian model in order to calculate their area for each protein, andthereby the concentration of the protein in the sample.

The peak area determined for a protein in the soluble phase wasthereafter corrected by the effective protein content determined by theKjeldahl method (described thereafter) and normalised by the peak areaof the corresponding protein in the total sample.

The amount of proteins present in the soluble phase after centrifugationcan also be measured by Kjeldahl method using a conversion factor of6.38 for milk proteins.

Kjeldahl Method:

Kjeldahl is a general method allowing the determination of totalnitrogen, using a block-digestion apparatus and automated steamdistillation unit.

This method is applicable to a wide range of products, including dairyproducts, cereals, confectionary, meat products, pet food, as well asingredients containing low levels of protein, such as starches. Nitrogenfrom nitrates and nitrites is not determined with this method. Thismethod corresponds to the following official methods: ISO 8968-1/IDF20-1 (milk), AOAC 991.20 (milk), AOAC 979.09 (grains), AOAC 981.10(meat), AOAC 976.05 (animal feed and pet food), with small modifications(adaptation of catalyst quantity and sulphuric acid volume fordigestion, and adaptation of boric acid concentration for automatedsystem).

Principle of the method: Rapid mineralisation of the sample at about370° C. with sulfuric acid and Missouri catalyst, a mixture of copper,sodium and/or potassium sulfate, which transforms organically boundnitrogen to ammonium sulfate. Release of ammonia by addition of sodiumhydroxide. Steam distillation and collection of the distillate in boricacid solution. Acidimetric titration of ammonium.

Apparatus: Mineralisation and distillation unit in combination with atitration unit.

Manual, semi-automated and automated conformations are possible.

These methods are known from a skilled person in the art of frozenconfectionery who has a good knowledge of proteins.

The reduction of fat in frozen confectioneries without compromising theindulgent quality of the product is one of the main challenges faced bythe industry. The present invention is overcoming this issue inproviding low fat or even non-fat products with similar texture andsensory attributes than those having higher fat contents in terms ofcreaminess and flavour delivery.

Furthermore, the benefit of the system according to the inventionextends to other parts of the cold-chain distribution of such products,in that products which have gone through typical heat shock ordistribution abuse maintain the smooth, creamy texture longer than otherproducts that are subjected to the same treatment.

Thus, the present invention proposes a new way in which a low fat,preferably natural frozen confectionery product which is stable and withsuperior sensory attributes may be manufactured.

EXAMPLE Frozen Confection

Test:

Mix 1:

Wt % in the Ingredients composition Water 67.8 Sweet whey powder 16.9Skim milk powder 14.7 Lemon Juice concentrate 0.6 TOTAL 100

Mix 1 has a pH of 6.0 at 25° C.

Mix 1 was processed under the following conditions:

-   -   Mixing    -   Pre-heating at 72° C.    -   homogenisation at 40 bar (total pressure)    -   Heat treatment at 86° C. for 30 seconds    -   cooling at 4° C.

A second mix 2 having the following formulation was prepared:

Mix 2:

Wt % in the Ingredients composition Water 49.2 Sugar 14.5 Glucose syrup60% 21.3 Stabilizers and emulsifiers 0.6 Dextrose 2.1 Skim milk powder1.4 Coconut fat 10.9 TOTAL 100

Mix 1 was then mixed with mix 2 to form an ice confectionery mix in thefollowing proportions:

Mix 2 70.5 wt % Mix 1 29.5 wt %

The ice confectionery mix was pasteurized at 86° C. for 30 seconds,cooled at 74° C. and then frozen at −6° C. with an overrun of 100%. Thefrozen product was then hardened at −40° C.

As a control, an ice confection mix consisting in mix 1 without lemonjuice concentrate and mix 2 as defined above was prepared. Said mixturehas a pH of 6.7 (no adjustment was made). The mixture was thenpasteurized at 86° C. for 30 seconds, cooled at 74° C. and then frozenat −6° C. with an overrun of 100%. The frozen product was then hardenedat −40° C.

A panel of experts tested the product prepared according to the processof the invention and the control and concluded that the texture of theproduct of the invention was significantly smoother than that of thecontrol.

The invention is claimed as follows:
 1. A frozen confectionery productobtained by a method comprising: subjecting a composition having a pHbetween 5.6 and 6.5 and comprising at least 7 wt. % of dairy proteincomprising a protein source selected from the group consisting of liquidfresh milk, milk powder, standardised milk powder, skimmed milk powder,acid casein, sodium caseinate, and combinations thereof to a heattreatment at a temperature between 80° and 140° C. for a time period of5 seconds to 30 minutes to at least partially form protein aggregatescomprising casein and whey protein; mixing the heat treated compositionwith further ingredients to form an ice confectionery mix; pasteurizingthe ice confectionery mix; and freezing the pasteurized iceconfectionery mix to form the frozen confectionery product.
 2. Thefrozen confectionery product of claim 1, comprising between 0.5 and 4wt. % of coagulated protein system comprising the protein aggregates. 3.The frozen confectionery product of claim 1 having an average equivalentdiameter of fat globules below 10 microns.
 4. The frozen confectioneryproduct of claim 1 having a non-sedimentable protein content below orequal to 60%.
 5. The frozen confectionery product of claim 1 having anon-sedimentable protein content below or equal to 50%.